Fastener system

ABSTRACT

A fastener system including a nut body and a helical thread insert. The nut body having an internally threaded bore containing a plurality of bore threads, and at least one bore obstruction. The helical thread insert formed to create a plurality of internal HTI threads and a plurality of external HTI threads, with the helical thread insert received in the internally threaded bore and not occupying all of the plurality of bore threads, and having its movement limited by the bore obstruction. The helical thread insert having threads with both circular end profiles and a non-circular end profile. The non-circular end profile including at least three straight segments, and located between circular threads.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/989,131, filed on May 24, 2018, which claims priority to U.S.Provisional Patent Application Ser. No. 62/510,495, filed May 24, 2017,U.S. Provisional Patent Application Ser. No. 62/561,454 filed Sep. 21,2017, U.S. Provisional Patent Application Ser. No. 62/553,190 filed Sep.1, 2017, and U.S. patent application Ser. No. 15/595,620 filed, May 15,2017, the disclosures all of which are hereby incorporated by reference.

STATEMENT REGARDING FEDERAL GRANTS

Not Applicable.

BACKGROUND

The present disclosure relates to a new type of nut where a helical wireinsert that is used as part of a nut, along with a retained cap to locka fastener in place. In a preferred embodiment, the new fastenerprovides a new category of threaded nuts for fasteners.

Locking fasteners are widely used in attaching equipment to thestructure of a wide variety of machinery and vehicles. In one example,locking fasteners are used in an airframe, including for attaching partsto an aircraft fuselage. Other examples include installations in avariety of vehicles, such as automobiles, agricultural equipment,construction equipment, railroad equipment, trucks, trains, militaryvehicles and weapon systems, defense, space craft and for many othercommercial vehicles, (e.g., tractors, earth moving equipment, conveyorsystems, yard equipment) and the like. In particular, aircraft jetengines are often attached to the airframe with barrel nuts that includea locking feature. In addition, the same or similar fasteners are usedin a variety of situations, such as industrial equipment, farm equipmentand other equipment where vibration and motion control is required.

Existing locking fasteners are generally classified as using either a“prevailing torque” locking system, or using a “positive lock” lockingsystem. Prevailing torque fasteners typically will utilize somestructure that allows a threaded fastener to be advanced, i.e.tightened, to a particular torque, and then the locking structureretards the reverse backing out of the threaded shaft. A commonprevailing torque fastener implements a plastic insert in the cap of anut, with the insert bearing against the threaded shaft. The resilientnature of the plastic insert bears against and retards the backing outof the threaded shaft until a torque sufficient to overcome theprevailing torque is applied. The application of prevailing torque nutswith a resilient insert of Vespel™ material has achieved wideimplementation in aircraft, despite the limitations of this particularprevailing torque locking fastener.

Positive lock locking fasteners are represented by a physical barrier tothe backing out of a threaded shaft in a fastener system. A commonexample of a positive lock is the insertion of an appropriately sizedcotter pin in a cross bored hole through a shaft that prevents advanceof a fastener along a threaded shaft, either with a castellated nut ornut cap, or without an accompanying cap.

Vespel™ inserts are made from a polymide material and are often usedwith locking or self-locking fasteners. Available fastener systems aregenerally less than fully acceptable because of the available lockinginserts are expensive and installation of a locking insert, such as aVespel™ insert, is often difficult. An additional difficulty in usingsuch inserts is that the bolt fasteners must be driven into the insertto maintain the specified torque tolerance when used in an environmentthat imposes a wide range of temperatures and vibration patterns. Forpurposes of reliability and safety a positive locking mechanism isconsidered important. Currently, the only effective locking or retainingsystem available for aircraft us is a collar made of resilient material,such as Dupont Vespel™. Commonly Dupont Vespel SP polymide componentsare machined or cut into a disk shape and then inserted as a collararound a fastener nut.

Locking fasteners which use inserts such as resilient inserts formed ofVespel™ have many limitations. Importantly, such inserts are expensive,as the plastic material must be approved by OEM users and theproprietary material in Vespel™ cannot be substituted by unapprovedalternatives from third parties. The use of resilient inserts also hasmany issues such as a) the inserts are easily-damaged duringinstallation b) the inability to reuse resilient inserts forreinstallation of components, and c) the limitation to the shape offasteners when using a resilient collar. These current systems aregenerally limited, and could be substantially improved with analternative substitute to a resilient insert fastener. Anotherdisadvantage of existing systems is the limited number of cycles ofinsertion and removal that are within specified limits. Furthermore,there is an undesired inconsistency between torque values between theearly cycles of use, and when the fastener is finally replaced. It is agoal of certain specifications that torques have limited variabilityover 15 cycles including prevailing torque and breakaway torque.

A variety of threaded inserts have been available for the last 50 years.One example of a threaded insert was invented by the Heli-CoilCorporation of Long Island, N.Y. A “heli-coil” insert was generallyutilized to repair damaged threads in a complex part, such as an engineblock, that could not be easily be replaced or would be unreasonable toreplace due to a single damaged thread. With heli-coil type insert, theexisting threads are drilled out and the hole is retapped for thethreaded insert. After insertion of the threaded insert, the originalthread geometry can be recreated by the insert. One example of thehelicoil type thread insert is disclosed in U.S. Pat. No. 2,607,259 byJ. O. Forster, issued Aug. 19, 1952.

Another example of a threaded insert is the “Spiralock™” fastener,available from Stanley Engineered Fastening of New Britain Conn. Thespiralock-type fastener provides an insert that serves to retain aninserted male fastener so long as the fastener is driven to have anassembly clamp load. Spiralock-type fasteners are not considered aprevailing torque locking fastener, because there is no locking actionif the terminal torque requirement is not maintained.

There is a continuing need for specialized fasteners that function toretain a male thread through a range of insertion, even if a terminaltorque is not maintained. In essence it is highly desirable for the malefastener to be inhibited from backing out and completely releasing fromthe fastener. Typically the nut or female fastener backs off the boltportion of male fasteners, while the nut usually rotates off the bolt,while the bolt remains in a stationary position.

Further, it is desirable to provide an insert that provides reusablethreads, and an insert providing threads that are stronger than theparent material, and that increase the strength of parent material,thread insert, and fastener combination over the net strength withoutthe thread insert. A thread insert will have a larger diameter than themale fastener and thus provides an increase in the bearing area of thefastener.

Other previous attempts in the aircraft industry to improve on lockingfasteners have resulted in a variety of fasteners, each of which havecertain limitations. For example, U.S. Pat. No. 5,127,782 issued Jul. 7,1992 discloses a fastener system as a self locking castellated nut.

For instance, the Shur-Lok “Sta-Lok™” system is approved for use inaircraft such as helicopters, and utilizes a series of small serrationsto hold a fastener nut in place after being torqued to a givespecification.

An improved fastener system is desired by manufacturers and retrofittersto reduce the cost of current fasteners, and it is also desirable toenable labor savings along with improved assembly processes, andimproved maintainability, reparability, overhauling, fastenerreliability and strength.

SUMMARY

The present disclosure relates to a new type of nut comprising a helicalthread insert as part of a nut body, along with a retained clasp to locka fastener in place. In a preferred embodiment, the new fastenerprovides a new category of threaded nuts for fasteners.

The present disclosure is embodied in a fastener comprising a nut bodyand an associated Lockone clasp. The Lockone clasp may be maintained inits association by one or more Lockone clasp retainers, with saidretainers essentially formed as a clip projecting a face of the nut bodyand disposed pawl shaped clips, affixed to the nut body, and arrayedabout an arc about the edge of the thread bore. In a preferredembodiment, there are two or more retainers, or three or more or aseries of one or more retainers forming an arc and another retainerspaced apart. The retainers hold a Lockone clasp in association with thenut body, and allowing for the clasp to flex about the nut body relativeto the clasp thread ring. The nut body is formed with an internallythreaded thread bore with said internal threads, partially filled byhelical thread insert. In a preferred embodiment the helical threadinsert is a locking helically wound wire thread insert. In anotherpreferred embodiment the helical thread insert is a free runninghelically wound wire thread insert.

In another embodiment, the disclosure provides for a method ofmanufacturing a fastener comprising a nut complementary with a threadedshaft comprising providing a fastener that includes a nut with a threadbore internally threaded to accept a helical wire insert; a helical wireinsert with an external thread that mates with the internal threads ofthe thread bore, and internal threads that are compatible with thespecified threads for accepting an externally threaded shaft, saidcomplementary shaft capable of being driven by a given torque into thehelical wire insert, and the nut with helical wire insert furthercomprising a helical wire insert that increases the strength of thefastener over the strength of a nut or a threaded shaft. The disclosedmethod further comprises a helical wire insert that increases thestrength of the fastener assembly over the strength of a nut or athreaded shaft without a helical thread component. Furthermore, themethod further comprises a free running nut.

BRIEF DESCRIPTION OF THE DRAWINGS

For a fuller understanding of the nature and advantages of the presentinvention, reference should be had to the following detailed descriptiontaken in connection with the accompanying drawings, in which:

FIG. 1 shows a view of a fastener using the insert system with a Lockoneclasp;

FIG. 2A shows a perspective view of a fastener using a retainer latchand a Lockone clasp;

FIG. 2B shows a top plan view of a fastener using a retainer latch and aLockone clasp;

FIG. 2C shows a side elevation view of a fastener using a retainer latchand a Lockone clasp;

FIG. 3A shows a perspective view of a locking fastener and a helicalthread insert components for use with the fastener assembly;

FIG. 3B shows a cross-sectional view of a locking fastener and a helicalthread insert components for use with the fastener assembly;

FIG. 3C shows a perspective view of a helical thread insert componentfor use with the fastener assembly;

FIG. 3D shows a side elevation view of a helical thread insert componentfor use with the fastener assembly;

FIG. 3E shows a top plan view of a helical thread insert component foruse with the fastener assembly;

FIG. 3F shows a cross-sectional view of a helical thread insertcomponent for use with the fastener assembly;

FIG. 4A shows a perspective view of the components of the Lockonefastener system;

FIG. 4B shows a side elevation view of the components of the Lockonefastener system;

FIG. 4C shows a top plan view of the components of the Lockone fastenersystem;

FIG. 4D shows a bottom plan view of the components of the Lockonefastener system; and

FIG. 4E shows an exploded perspective view of the components of theLockone fastener system.

DETAILED DESCRIPTION

Disclosed herein is a new apparatus and associated method for securingequipment to an underlying structural support. In particular, disclosedis a locking fastener embodied as an improved nut useful for providingreliable attachment of components of stationary objects to structuralmembers, where attachments may be subject to vibrational loosening. In apreferred embodiment, the new lock on fastener is used to attachcomponents to communications and electrical service towers.

As disclosed herein such lock on clasp fastener assembly systemtypically is a nut configured to accept a male fastener, and provide fora desired set of torque tolerances including locking, unlocking, bothduring installation or removal.

FIG. 1 shows a side view of the newly disclosed fastener, that providesa nut body with a lock on clasp component. In FIG. 1 , fastener 200 isshown with a nut body, 210, a threaded shaft 220, commonly as a bolt,and a lock on clasp coil 230. Nut body 210 is shown embodied as a hexnut with a series of six points, as at 212, and six faces, as at 213.Nut body 210 is preferably internally threaded to accept a helicalthread insert (HTI) within the threadbore and the HTI provides thethreads that carry the threads of shaft 220.

Threaded shaft 220 is formed with a series of threads 222, and thethreads are comprised of thread lands 222 and thread grooves 224. Thethread geometry, as in lands 222 and grooves 224 can be formed in avariety of manners, with many thread geometries commonly used by thoseskilled in the art.

Shown in the FIG. 1 , Fastener 200 has an externally hexagonal shape asis common for machine nuts. Those skilled in the art will recognize thatother nut shapes are applicable to the disclosure. The nut body 210 isformed with a thread bore, and the thread bore is tapped to conform tothe desired thread pattern. Threads can be formed to fit typicallyavailable standard thread inserts, for example, STI threads. As notclearly visible in FIG. 1 , a helical thread insert essentially fillsthe threads of nut body 210. When a bolt or stud is such as threadedshaft 220 is threaded into the fastener, the counter rotation of theinsert may be limited by the action of a helical thread insert,depending on the type of insert used. See FIG. 3 for further disclosurerelating to the helical thread insert.

The lock-on clasp helix is marketed by Kato Fastening Systems of NewportNews, Va., USA, as the LockOne™ locking product. The lock-on (Lockone)helix acts as a positive locking retainer that occupies approximatelythe three terminal threads of the distal end of a threaded shaft. Byco-tightening the lock on helix with a nut body the lock on helixprevents the advance of the nut body along a threaded shaft.

In FIG. 1 lock-on helix 230 is formed of steel, such as 304 stainlesssteel WPB, and comprises a coil within a coil. Outer coils 232 provide aseries of generally planar flat faces, as at 236, between a series ofsix vertices, as at 237. When relaxed, the outer coils adopt a hexagonalconformation of the outer coils 232. Inner coils 233 engage within thethread grooves 224, and as they engage such threaded shaft geometricchange on the orientation of outer coils 232 is imposed. The result isthat the loaded lock on helix adopts a twelve point conformation, withpoints 212 aligning with arrows 12 aligning between the points of thehex nut body 210. When adopting the “twelve point” conformation, asshown in FIG. 2 , the lock on helix is retarded from rotating about thethreaded shaft 220. In order to remove a nut body locked by the lock onhelix, a twelve point socket is used to counter rotate the upper set ofcoils so that they align with the inner set of coils, releasing the gripof inner coils 233 from the threaded shaft.

It is a further embodiment of this disclosure that the disclosed nutbody provides a feature for retaining the lock on helix to the nut body.Retainer clip 216, as shown in FIG. 2 is machined as part of the processof manufacturing nut body 210. The retainer clip 216 is formed with athroat 217 that accepts the body of Lockone clasp helix 230, and a latch218 that retains the Lockone clasp helix about the retainer clip throat.

Turning to FIG. 2 , a series of views of an alternative embodiment areshown. Fastener 100 has an externally hexagonal shape as is common formachine nuts. Those skilled in the art will recognize that other nutshapes are applicable to the disclosure. The hex nut body 120, is formedwith a series of evenly spaced vertices, as a hexagonal nut. A flange126 is shown at the base (bearing face) of the nut body. The nut isformed with a thread bore, 124. The thread bore is tapped to conform toa desired thread pattern. Threads can be formed to fit typicallyavailable standard thread inserts, for example, STI threads. As notclearly visible in FIG. 2 , a helical insert 130 essentially fills thethreads of fastener 100. A locking or free-running helical insert couldbe used.

Also shown in connection with the fastener 100 is lock clasp 110, formedof resilient metal material, and marked by Kato Industries as a“LockOne™” component. In connection with this disclosure, the Kato LockOne component is also termed a “Lockone clasp.” When in the conformationshown in FIG. 2 , a compressed configuration, the Lockone clasp 110presents a series of vertices which may align with the vertices of thenut body. The Lockone clasp is retained with the nut body by retainerlatches 140. Further, the locking cap can be further covered with aresilient material such as a rubberized sheath. (not shown)

It is an additional embodiment of the disclosure that the nut body maybe formed of more than one material. For instance, a molded nut bodyprovided with a stainless steel helical wire insert may perform as wellas any nut body formed only of mild steel. In addition, a nut body couldbe formed with a metal core, such as a steel core, and then be comolded,over molded or impregnated with a plastic filler.

FIG. 2B and FIG. 2C show a side view and a top view of the fastenerassembly 100, that provides a nut body with a lock on component, toassist in understanding the assembly. Fastener 100 is provided with tworetainer latches 140, as L-shaped pawls, that are in an opposedposition, and are integrated with the structure of nut body 120. Nutbody 120 is preferably internally threaded to accept a helical threadinsert (HTI) within the threadbore and the HTI provides the threads thatcarry the threads of a shaft.

As a bolt is inserted into the assembled locking fastener, such asfastener 100, or fastener 200, rotation of the bolt will engage helicalthread insert, if one is installed. FIG. 3 demonstrates theconfiguration of a helical thread insert in connection with a nut body.

As shown in relation to FIG. 1 , an inserted threaded shaft expands aninstalled helical thread insert to bear against the inner surface of thethread bore. As the bolt advances into the helical insert, additionalsegments of the helical insert are expanded and bear against the threadbore body. In one embodiment, the bolt is advanced entirely through thehelical insert and thread bore body, and is finally torqued to aspecified torque. In such case, the characteristics of the helicalinsert will serve to retain the bolt in position and resist anybacking-out of the bolt to a reverse torque specification determinableaccording to the characteristics of the helical insert. Properlyinstalled, the helical insert will bear against both the bolt and thethread bore body, retaining the inserted bolt.

In an alternative embodiment, the bolt is inserted only a portion of thedepth of the helical insert, and the portion of the helical insert thatis bearing against the bolt and the thread bore body will retain thebolt to a determinable reversing torque.

A threaded insert that utilizes established thread geometry, such as“Standard Thread Insert” (STI) or met common thread standards would bean advantage, as it would not be necessary to utilize specializedthreads, or specialized tools or gauges for using any such specializedthreads.

If utilizing an insert to provide prevailing torque retention, it shouldbe immediately apparent to a technician that a prevailing torque insertis in use. Moreover the insertion torque due to the retention insertshould be measurable along with the insertion torque of the fasteneritself. In certain applications, it is necessary to utilize a gasketmaterial between two mating surfaces. The retention insert shouldprovide for maintaining locking action throughout a range of compressionof gasket material.

FIG. 3 shows a series of views to assist in understanding of the use ofa helical thread insert with the new fastener system shown. FIG. 3Ashows a perspective view of a locking fastener with a helical insert,embodied as a nut. Fastener 1000 has an externally hexagonal shape as iscommon for machine nuts, with nut faces 1002-1007. Those skilled in theart will recognize that other nut shapes are applicable to thedisclosure. The nut body 1012 is formed with a thread bore, 1010, (alsoreferred to as a thread bore body 1012) by drilling or hot pressing. Thethread bore is formed by tapping, machining or roll forming to conformto the desired thread pattern. Threads 1020 can be formed to fittypically available standard thread inserts, for example, STI threads.As shown in FIG. 3A, helical insert 1030 essentially fills the threadsof fastener 1000 thread bore 1010 threads 1020. When a bolt or stud isthreaded into the fastener, the counter rotation of the insert may belimited by the action of the helical thread insert, if such insert is aprevailing torque HTI (See FIG. 3C-F). The thread insert is commonlyinserted by use of a tool. In fastener 1000, the HTI is trapped in thethread bore by a physical barrier, such as detent 1040, or otherobstruction.

FIG. 3B shows a cross section of an exemplary fastener, as if sectionedalong line 2-2 of FIG. 3A. Fastener 2000 is provided with a helicalinsert 2030 that occupies only a portion of the depth of the fastener.Fastener 2000 is penetrated by thread bore 2010, and the thread bore2010 has been tapped to provide threads 2020. Helical insert 2030 may beselected from a wide range of available helical inserts to occupyapproximately ½ of the depth of thread bore 2010. As such, the fastener2000 provides both material of the fastener nut body itself at region2032 to hold a bolt or stud, a thread insert portion at 2030 and alocking portion at region 2034 to retain an inserted bolt. Detents 2036and 2038 can be formed after insertion of the helical thread insert,trapping the HTI within the thread bore, but allowing relaxed travelabout the threads by the thread insert. Detents 2036 and 2038 are formedfor example, but not limited to, by upraising a segment of the threadbore, interrupting the thread bore, or by affixing barrier material(such as by spot welding) about the threads forming the inner surface ofthe thread bore.

Helical thread inserts can act as prevailing torque locking nutsdepending on the HTI used in a particular application. FIG. 3C-F showone version of such an insert that will act as a prevailing torque HTIwhen used with the fastener systems disclosed. FIG. 3A shows aperspective view of such an HTI. Insert 300 is formed of polygonal wire,so that the insert presents an internally threaded threadbore, 320, ofthreads 322 with a series of HTI faces, 324-329 (for example), whichproject into the final threadbore. The HTI is formed in the typicalapplication with external threads 330 remaining compatible with an STIthread. The side view in FIG. 3B shows a generally cylindrical HTI, withthe threads 330 being interrupted by modified threads, as indicated at325-327. As shown in FIG. 3 , a selected portion of the threads can bemodified to change the running characteristics of the internal threadsof the HTI (and also to a modifiable extent to the external threads330). A wide variety of internal threads are available, such as thosefrom Kato Fastening Systems, with differing characteristics of back outand prevailing torque resistance.

An end view of a prevailing torque locking HTI is shown in FIG. 3C, anda cross sectional view in FIG. 3D. From the top view shown in FIG. 3C,the internal threads 322 of threadbore 320 combine to create a generallycircular end profile, with the HTI prevailing torque faces 326-329interrupting the smooth profile of the internal threads. In practice,the characteristics of a helically threaded insert, such as insert 300installed in a nut body such as fastener 1000, will serve to retain aninserted bolt in position and resist any backing-out of the bolt to areverse torque specification determinable according to thecharacteristics of the helical wire insert. Properly installed, thehelical insert will bear against both the inserted bolt and the threadswithin thread bore body, thus resisting the initial back-off movementand further retaining the inserted bolt against a reverse prevailingtorque.

Helical inserts have been used for some time in industry forapplications that substantially differ from those disclosed, including,for instance, as a means to repair damaged threads. A variety of suchspecifications and applications are provided by the manufacturer ofhelical wire inserts, such as from Kato Fastening Systems, Inc. Helicalcoil inserts are helically-wound inserts that function in fasteners toprovide durable screw threads. Kato brand “CoilThread™” Inserts are madeof cold-rolled No. 304 stainless steel wire (AS7245), work-hardened to atensile strength above 200,000 psi, and a hardness of Rc 43-50. KatoCoilThread inserts are available in a variety of wound thread sizesincluding Unified Coarse (UNC), Unified Fine (UNF) and Metric threadsizes. It should be apparent to those skilled in the art that thesethread types are only some of the variety of helical coil inserts. Whenhelical coil inserts are assembled in “STI” (Standard Thread Insert)tapped holes, helical coil inserts can form standardized Unified Coarse(UC) or Unified Fine (UF) threads that conform to National Bureau ofStandards Handbook H-28, and meet screw thread standards according toU.S. Federal classification. Helical coil inserts can also be producedthat fit a variety of other thread standards, such as for instance, willalso accommodate UNJ, MIL-S-8879, and male threaded fasteners. Furtherexamples are shown in the 2015 CoilThread Inserts and Tools productcatalog of Kato Fastening Systems, Inc. of Newport New, Va. As describedbelow, the selection of a particular helical thread insert (HTI) may bebased on the particular application for which a fastener is intended.Certain thread inserts may be configured with a geometry that is suitedfor use as a locking HTI. Other insert geometry may be better adaptedfor a free-running HTI.

FIG. 4 shows a series of views of one embodiment of the disclosure,identified as fastener 400. The identified components in FIG. 4 arecalled out and described below. Nonetheless, to assist the comprehensionof the disclosure, the identified components are also identifiedherewith as follows: fastener 400; nut body 410; base flange 412; nutbody hex face 414; nut body hex face 416; Lockone clasp 420; Lockoneouter ring 422; Lockone inner ring 424; Lockone thread ring 426;transition arm 428; lock retainer 430; variant lock retainer 432;helical thread insert 435; and threadbore 440.

FIG. 4A shows a perspective view of the fastener 400 with a nut body andLockone clasp. The fastener is formed with a hexagonal nut bodycylinder, with a base flange portion 412 of nut body 410. Nut body hexfaces 414 and 416 are exposed to view and are accessible to the tool,such as a socket or nut driver used with the fastener. Fastener 400surrounds a thread bore 440, the thread bore bearing internal threadsessentially filled by a helical thread insert that is hidden from viewin FIG. 4A. The fastener 400 consists essentially of Lockone clasp 420surmounting and mated to a flanged nut body (as 410) carrying aninternally disposed helical thread insert (not shown). The Lockone clasp420 has an outer ring 422, that alone, and relaxed generallyapproximates a hexagon, along with an inner ring 424, also generally ahexagonal, connected to a thread ring 426 that bears against a threadedshaft inserted into the fastener. The relative flexing of the inner ringand the outer ring bring force to bear from the Lockone rings against aninserted bolt or stud. To release the grip of the Lockone clasp, andfreeing an inserted shaft to turn requires rotation of the inner ringand outer ring relative to one another (by use of a 12-point socket, forexample) and relaxing the forces applied to the thread ring.

The present disclosure combines a Lockone clasp, integrated with a nutbody, and a helical thread insert. If a prevailing torque lockinghelical thread insert is utilized, the fastener 400 will provide afastener that is equipped to lock at a predetermined prevailing torque,and also be clamped in place by the action of a Lockone retainer. Aswill be further described, along with the following figures, fastener400 provides retainers that wed the Lockone clasp to the nut body.

In many situations, the redundant locking mechanisms would not benecessary. In certain high demand situations, a locking approach thatprovides a prevailing torque locknut, and the positive locking securityof the Lockone clasp is warranted. In one example of such a high-demandapplication, communication towers that are bolted together from modularcomponents may demand such extra security. In one example of such acommunication tower, a tower installed in a generally inaccessiblelocation such as a mountain side or building roof, can with the properequipment be quickly assembled and torqued to a predeterminedspecification. Such towers may be exposed to sever elements, and subjectto high wind forces. On some occasions, wind forces combined withharmonic flexing of the structure under load can over time, loosenconnecting bolts that were initially torqued to specification. Failureof threaded connections in such communications towers can create adisastrous combination, with an important tower collapsing, causing lossof service, property damage and injuries, and lead to significantrecovery costs.

The exploded view in FIG. 4E reveals the Lockone retainers, shown by wayof example at 430 and 432. As shown in FIG. 4E, the retainers areessentially formed as an integral clip projecting from the exposed faceof nut body 410 (as opposing the bearing, or flange face). Retainers 430are shown as a series of similarly sized and disposed pawl shaped clips,attached to the nut body, and arrayed about an approximately 270 degreearc around the edge of the thread bore. Free standing retainer clip 432is shown as being wider, for instance, than the individual clips 430,and disposed in a location generally equidistant from the separatedretainer clips 430. As shown, each of clips 430 occupy generally 30degrees of the edge of thread bore 440. Fewer or wider clips with adeeper projection may be adaptable for particularly favored embodiments.The function of retainers 430 and 432 is to hold the Lockone clasp inplace, while allowing for the clasp to flex about the nut body as theouter ring and inner ring move relative to one another and the threadring. It is considered important, if not essential that the presentlydisclosed form of Lockone clasp is formed with a transition arm, as at428 (along with an inner transition arm hidden in the view in FIG. 4E)that must connect the inner ring to the thread ring.

In FIG. 4D, fastener 400 is shown from a bottom or flange side view.Fastener 400 is formed with a thread bore 440, with internal threads433, partially filled by helical thread insert 435. The fastener istypically expected to be installed unidirectionally, with the flangeface 415 of base flange portion 412 of nut body 410 being drawn into aclose apposition with a structural member, or intervening washer. Nutbody hex face 414 and 416 are hidden by the flange in this view, as isthe Lockone clasp 420.

Turning to FIG. 4E, an exploded perspective view of the fastener 400 isshown. The fastener is formed with a hexagonal nut body cylinder, with abase flange portion 412 of nut body 410. Nut body hex faces 414 and 416are exposed to view in this view. Fastener 400 is formed with a threadbore 440, with the internal threads of threadbore 440 shown asessentially filled by a helical thread insert 435. As previouslydescribed, the fastener 400 consists essentially of lock one clasp (see420) mated to a flanged nut body (as 410) carrying a helical threadinsert (as 435). The Lockone clasp 420 has an outer ring 422, generallyas a hexagon, an inner ring 424, also generally a hexagon, connected toa thread ring 426 that bears against an inserted threaded shaft, such asa bolt or stud.

The exploded view in FIG. 4E reveals the Lockone retainers, shown by wayof example at 430 and 432. As shown in FIG. 4E, the retainers areessentially formed as an integral clip projecting from the exposed faceof nut body 410 (as opposing the bearing, or flange face). Retainers 430are shown as a series of similarly sized and disposed pawl shaped clips,attached to the nut body, and arrayed about an approximately 270 degreearc around the edge of the thread bore. Free standing retainer clip 432is shown as being wider, for instance, than the individual clips 430,and disposed in a location generally equidistant from the separatedretainer clips 430. As shown, each of clips 430 occupy generally 30degrees of the edge of thread bore 440. Fewer or wider clips with adeeper projection may be adaptable for particularly favored embodiments.The function of retainers 430 and 432 is to hold the Lockone clasp inplace, while allowing for the clasp to flex about the nut body as theouter ring and inner ring move relative to one another and the threadring. It is considered important, if not essential that the presentlydisclosed form of Lockone clasp is formed with a transition arm, as at428 (along with an inner transition arm hidden in the view in FIG. 4E)that must connect the inner ring to the thread ring.

As described herein, composite fasteners are considered a composite ofmore than a single component. For instance, common machine nuts areformed of a metal such as mild steel, and comprise only a singlecomponent. A coating, such as zinc plating, as considered in the presentdisclosure is not a composite fastener. The Lockone locking nuts, asshown in FIG. 1 and FIG. 4 , for instance, are composite fasteners inthe terms of the present disclosure as such a nut is a composite of twoor more individual components. A nut could be formed with an inherentthread bore, retainer clips, and an installed Lockone clasp, and as suchis a composite of two physical components. Another nut, such as nutassembly 400 of FIG. 4 , is a composite of a nut body, a helical threadinsert, and a Lockone clasp. Prior to the present disclosure, there hasbeen no enabling disclosure of any kind that discloses such a threeelement composite fastener.

The present disclosure is further amenable to adaptation to nut bodiesformed of multiple materials, and are composite fasteners furthercomprised of a nut body core, and a lightweight formed matrix completingthe nut body. Such as composite fastener can be comprised of a compositenut body, with the addition of a helical thread insert, and theinstallation of a Lockone clasp element.

The composite nut bodies of fasteners as described could be formed to be“ultra lightweight,” as either a free running nut or as a nut with ahelical thread locking insert as a locknut. Such nut bodies (nuts)comprise hybrid metal and plastic nut. The metal, such as hardened steelor steel alloy can provide the structural framework, and the final shapebe formed by a plastic “layers.” There can be multiple layers of plasticor composite material that fill the space between metal wafers. Nut bodymaterials can be aluminum, steel/alloy steel and corrosion resistantsteels (e.g., stainless steels).

In yet another embodiment, the spaces between metal wafer layers can beleft open rather than over-molded with a plastic. In some compositionsof plastic the over molding plastic would only add additional costwithout any significant structural benefit (other than appearance). Thelocknuts forms of such fasteners would include locking helical wireinserts and the “non-locking” nuts would use free running helical wireinserts.

In still another embodiment, the nut body is formed entirely of plastic,except for the helical wire inserts for the running threads. Suchcomposite nuts can be formed with either locking and free running HTI's.Certain plastic nuts could be solid plastic and look like traditionalnuts (only with the nut body made from plastic) or also be ultra lightweight versions with wafer layers of plastic, as described above.

Nuts formed only of plastic or composite material with helical wireinserts are believed to provide the capability for the higheststrength-to-weight nuts available in any market. In addition, the HTInuts provide a much more consistent lock and torque characteristics thanmechanically crimped or plastic insert nuts currently available. Thusthese fasteners can maintain acceptable prevailing torques over moreinstallation cycles as compared to conventional material nuts. Anadditional benefit is corrosion resistant benefits because of thestainless steel helical wire inserts are not corrodible, and the plasticnut body is not subject to ferro-oxidation either.

Existing locking fasteners are often characterized as either “positivelocking” or a “prevailing torque” locking fastener. In a positivelocking fastener, the threaded on portion of the fastener, typically anut, is mechanically held in its prescribed position by some type ofmechanical locking feature. For the nut to be released, or backed offfrom its specified final position, in a positive locking fastener, somemechanical failure must occur, such as shearing of metal, ordisplacement of retainer pin.

A prevailing torque mechanical fastener utilizes a specified torque oropposed frictional force to lock the fastener in place. Plastic inserts,such as a Vespel insert in a nut, offset locking washers, or crimpeddeformation fasteners are common examples of prevailing torque lockingfasteners. As disclosed herein, the helical insert functions as a newcategory of prevailing torque locking fastener.

Another existing type of locking nut fastener comprises a nut that hasbeen provided with a thread barrel that is a shape other than round, inparticular, an oval thread barrel. One current method of creating anoval thread barrel is to distort, or “crimp” a circular cross sectionnut barrel to a specified torque, distorting the round cross section toan oval cross section. Such crimped fasteners can function as aprevailing torque locking fastener, but have a number of limitations.These limitations include the difficulty in starting the crimped nut onthe thread of a bolt, due to the distortion of the circular crosssection. Nuts which are crimped at the time of use may be essentiallydestroyed by improper or over crimping. Furthermore, it is difficult toreproducibly create a desired fastener that performs within a narrowdesired range of prevailing torque. In these fasteners, the amount ofback-off resistance (i.e. the prevailing torque of the fastener) isdifficult to control and lacks consistency between different lots ofcrimped fasteners, and between installation events or between differenttechnician installers. See for instance, Barrett, R. T., “FastenerDesign Manual,” NASA Reference Publication 1228, March 1990.

Another type of crimped fastener utilizes three-point crimping (usuallyused on a larger sizes of nuts). Theoretically more points for crimpingare possible (for example four, or even more).

It is a further embodiment of the disclosed apparatus or device is useof a helical insert as a locking feature for female self-lockingfasteners in lieu of other traditional methods such as crimping (ovaland three or more point-) in order to deliver more consistent torqueperformance of the fasteners within the specimens of a given productionbatch. Such use of the new system provides for a reduced scrap rate offasteners, better maintainability of installed fasteners, and less riskof material performance issues such as micro crack or hydrogenembrittlement for instance. Implementation of the disclosure allows forthe elimination negative production issues, such as double crimping,unnecessary additional sorting or the like.

The helical thread insert of the current disclosure can be a fullsubstitute for crimped locking fasteners, and minimize the existingproblems with starting the fastener on a threaded shaft caused by thetolerances resulting from crimping of the fastener into an oval shape.

In accordance with the present disclosure, helical inserts for lockingfasteners can be utilized with a variety of types of fasteners. Inaddition, the same or similar fasteners are used in a variety ofsituations, such as industrial equipment, farm equipment and otherequipment where vibration and motion control is required.

These current systems are generally unacceptable because of the expenseof the locking inserts and difficulty in installing the locking Vespelinsert. An additional difficulty in using such inserts is the need forthe bolt fasteners driven into the insert to maintain the specifiedtorque tolerance when in use in an environment that imposes a wide rangeof temperatures and vibration patterns. As such a locking mechanism isconsidered important. Currently, the only effective locking or retainingsystem available for floating inserts is a collar made of resilientmaterial, such as Dupont Vespel™.

It should be recognized that the fasteners system disclosed isapplicable to a method of attaching components by providing a fastenerthat includes a thread bore internally threaded to accept a helical wireinsert, inserting a helical coil wire thread insert with an externalthread that mates with the internal threads of the thread bore, andinternal threads of the insert that are compatible with an externallythreaded bolt and capable of being driven by a given torque into thehelical thread insert, with the helical thread insert resisting thebacking out of the driven insert with a torque greater that the giventorque for driving the threaded shaft into the helical thread insert.

An unexpected result was obtained during the development of the presentapparatus and method of implementing locking fasteners using a HTI. Inorder to qualify newly developed fasteners for use in aircraft, aperformance protocol must be met and confirmed by testing of given lotsof fasteners. It is a preferred embodiment of the present disclosurethat the use of a helical thread insert provides a much higher fastenerstrength profile than was expected, and in addition a more consistentrepetitive torque profile than could be obtained by any existingqualified fastener. The implementation of a HTI with locking feature,created a larger thread bore in the fastener nut, and a stainless steelHTI insert in the thread bore created the fastener threads that wouldbear against and carry a threaded shaft (i.e. bolt or stud). Duringstrength testing of the new fastener structure, it was found that thefastener strength was substantially and unexpectedly increased. Inaddition, the torque profile of the fastener was significantly moreconsistent over the 15 cycles of insertion and removal for testing.

The present disclosure is further embodied in a method for manufacturingimproved threaded fasteners comprising a nut complementary with athreaded shaft, such as a bolt or stud. The method comprises providing afastener body that includes a nut body with a thread bore, the threadbore then being internally threaded to accept a helical wire insert,i.e. with an HTI thread. Such process can be automated, and either arolled thread or tapped thread provided (for instance). Next a helicalwire insert with the characteristics selected for a particularapplication is chosen, so long as the HTI has an external thread thatmates with the internal threads of the thread bore. The HTI may betanged or tangles, and further provided with locking surfaces or befree-running in certain uses. The HTI provides internal threads that arecompatible with the specified threads for accepting an externallythreaded shaft, a bolt or stud or other shaft desired for use with thefastener. The complementary externally threaded shaft is thus capable ofbeing driven into the fastener by a given torque by threading into thehelical wire insert. The nut body with helical wire insert functions asa nut for fastening parts, with the added benefit of further comprisingthat the helical wire insert increases the strength of the assembledfastener over the strength of a nut or a threaded shaft made of a singlematerial. Such nuts and fastener combinations can be optionallymanufactured to be either locking, or alternatively free running.

The method of manufacturing barrel nuts and other fasteners with aprovided HTI is superior to the methods using a resilient insert.Resilient insert nuts in general must have a counterbore recess machinedinto the distal portion of the nut to act as a receptacle to hold theresilient insert. Such manufacture requires precise machining tolerancesassociated with the counterbored dimensions. Further, the resilientinsert must be machined to a complementary size within acceptabletolerances. The resilient insert routinely must be placed in thecounterbore by hand and then a roll over or crimping operation isutilized to physically hold the insert in place. The crimping operationis relatively imprecise and excessive crimp leads to a higher drag on aninserted bolt, along with higher prevailing and break-away torques andhigher wear rate. As a result, resilient inserts often may not remainwithin specification for a prescribed 15 cycles life.

Fasteners supplied for aircraft manufacture and renewal must meetstringent quality specifications. Customers may require 100% of a batchsample of fasteners from each manufacturing lot pass a 15-cycle torqueprofile test with the fasteners required to meet a not-to-exceed minimumand maximum torque values for a 15 cycle test profile. Performance ofthe batch sample testing is very slow, labor intensive and consequentlyexpensive. Manufacturers of fasteners frequently are unable to qualify abatch sample to pass the 15-cycle torque testing. The resulting batchrejection would result in substantial reworking costs and potentiallylot scrapping costs.

The fasteners disclosed herein, i.e. providing nut bodies with a helicalthread insert, exhibit far more superior consistency in torqueperformance testing (both in locking and breakaway torques) not only inspecially handled batch samples, but more importantly, throughout theentire population of a given fastener batch.

In the instance that the helical wire insert used in the describedfasteners is somehow damaged during installation or removal, the HTI canbe readily replaced at minimal cost without the need for replacement ofexpensive to produce nut body, whether the nut body is formed ofstainless steel, Inconel or other material.

Additional benefits and features of the fastener system will be apparentto those skilled in the art. All of the examples should be considered tobe for the purpose of assisting artisans in understanding the broadscope of the disclosure, and should therefore not be taken in anylimiting sense.

While the invention has been described with reference to preferredembodiments, those skilled in the art will understand that variouschanges may be made and equivalents may be substituted for elementsthereof without departing from the scope of the invention. In addition,many modifications may be made to adapt a particular situation ormaterial to the teachings of the invention without departing from theessential scope thereof. Since certain changes may be made in the abovesystem without departing from the scope of the invention hereininvolved, it is intended that all matter contained in the abovedescriptions and examples or shown in the accompanying drawings shall beinterpreted as illustrative and not in a limiting sense. Also, allcitations referred herein are expressly incorporated herein byreference. All terms not specifically defined herein are considered tobe defined according to Webster's New Twentieth Century DictionaryUnabridged, Second Edition. The disclosures of all of the citationsprovided are being expressly incorporated herein by reference. Thedisclosed invention advances the state of the art and its manyadvantages include those described and claimed.

I claim:
 1. A fastener system, comprising: a nut body having aninternally threaded bore containing a plurality of bore threads, atleast one bore obstruction, and having a bore depth, wherein the nutbody is formed of aluminum; a helical thread insert formed to create aplurality of internal HTI threads and a plurality of external HTIthreads, the helical thread insert received in the internally threadedbore and does not occupy all of the plurality of bore threads, withmovement of the helical thread insert limited by the at least one boreobstruction, wherein: a) a portion of the external HTI threads mate witha portion of the plurality of bore threads; b) a majority of theinternal HTI threads are circular threads having a circular end profile;and c) at least one of the internal HTI threads is a non-circular threadhaving a non-circular end profile including at least three straightsegments, and the non-circular thread is located between circularthreads; and d) the helical thread insert is formed of stainless steel.2. The fastener system of claim 1, wherein the helical thread insert hasat least two circular threads on each side of the non-circular thread.3. The fastener system of claim 2, wherein the non-circular thread hasat least five straight segments.
 4. The fastener system of claim 3,wherein at least four circular threads are located on each side of thenon-circular thread.
 5. The fastener system of claim 4, wherein thehelical thread insert has an unequal number of circular threads on eachside of the non-circular thread.
 6. The fastener system of claim 5,wherein the helical thread insert is work-hardened to an insert tensilestrength of at least 200,000 psi.
 7. The fastener system of claim 6,wherein the helical thread insert has a Rockwell C hardness of 43-50RWC.
 8. The fastener system of claim 7, wherein the at least one boreobstruction is a detent formed by deforming one of the plurality of borethreads.
 9. The fastener system of claim 7, wherein the at least onebore obstruction is a detent formed of a welded barrier material. 10.The fastener system of claim 7, wherein the at least one boreobstruction includes two bore obstructions, and the helical threadinsert is trapped between the two bore obstructions.
 11. The fastenersystem of claim 7, wherein the plurality of bore threads includes nomore than 12 threads, and the helical thread insert includes no morethan 10 circular threads.
 12. The fastener system of claim 7, whereinthe nut body has a first end and a second end, the internally threadedbore extends through the nut body from the first end to the second end,the nut body having a hexagonal tool engagement surfaces extending fromthe second end toward the first end, and the first end having a circularflange with a bearing face and a curved transition region extendingtoward the second end and intersecting with the hexagonal toolengagement surfaces.
 13. A fastener system, comprising: a nut bodyhaving an internally threaded bore containing a plurality of borethreads, wherein the nut body is formed of a nut body material, and thenut body has a first end and a second end, the internally threaded boreextends through the nut body from the first end to the second end, thenut body having a hexagonal tool engagement surfaces extending from thesecond end toward the first end, the first end having a circular flangewith a bearing face and a curved transition region extending toward thesecond end and intersecting with the hexagonal tool engagement surfaces,and at least one bore obstruction in the internally threaded bore at thesecond end; a helical thread insert formed to create a plurality ofinternal HTI threads and a plurality of external HTI threads, thehelical thread insert received in the internally threaded bore and doesnot occupy all of the plurality of bore threads, with movement of thehelical thread insert limited by the at least one bore obstruction,wherein: a) a portion of the external HTI threads mate with a portion ofthe plurality of bore threads; b) a majority of the internal HTI threadsare circular threads having a circular end profile; and c) at least oneof the internal HTI threads is a non-circular thread having anon-circular end profile including at least three straight segments, andthe non-circular thread is located between circular threads; d) thehelical thread insert has at least two circular threads on each side ofthe non-circular thread; and e) the helical thread insert is formed of aHTI material different from the nut body material, and the helicalthread insert having a Rockwell C hardness of 43-50 RWC.
 14. Thefastener system of claim 13, wherein the non-circular thread has atleast five straight segments.
 15. The fastener system of claim 14,wherein at least four circular threads are located on each side of thenon-circular thread.
 16. The fastener system of claim 13, wherein thehelical thread insert has an unequal number of circular threads on eachside of the non-circular thread.
 17. The fastener system of claim 13,wherein the helical thread insert is work-hardened to an insert tensilestrength of at least 200,000 psi.
 18. The fastener system of claim 13,wherein the at least one bore obstruction is a detent formed bydeforming one of the plurality of bore threads.
 19. The fastener systemof claim 13, wherein the at least one bore obstruction further includesa second bore obstructions in the internally threaded bore at the firstend, and the helical thread insert is trapped between the two boreobstructions.
 20. The fastener system of claim 15, wherein the nut bodyis formed of aluminum, the plurality of bore threads includes no morethan 12 threads, and the helical thread insert includes no more than 10circular threads.